Methods of treating fibrous substrates generally may involve the application of at least one of a variety of treatment compositions. Such treatment compositions may be selected to provide or to restore certain desired physical or cosmetic characteristics to the fibrous substrate. However, unless an appropriate treatment composition is selected, the desired physical or cosmetic characteristics may not be obtained.
In the case of treating fibrous substrates comprising keratinous fibers, such as human hair, treatment compositions generally include shampoos, conditioners, colorants, styling compositions, and the like. Manufacturers of these hair treatment compositions may provide multiple versions of a type or brand of hair treatment composition, wherein each of the multiple versions is specifically designed to target a need or demand which is characteristic of a specific consumer segment and which may be based on physical or cosmetic differences of hair generally found between respective consumer segments. For example, a single brand of hair conditioner may offer a first version designed to deliver a level of conditioning appropriate for dry and damaged hair and a second version designed to deliver a level of conditioning appropriate for oily hair.
However, when a consumer is faced with the task of selecting a hair treatment composition from among the multiple versions of a hair treatment composition brand, the consumer may unknowingly select a version which is not designed to provide the characteristics desired by the consumer. In such a case, the consumer may be dissatisfied with the results of the selected version of the hair treatment composition brand. As a result of the consumer's dissatisfaction, the consumer subsequently may refuse to select any of the versions of that same hair treatment composition brand even though another version of that hair treatment composition brand may provide the consumer's desired hair characteristics. The occurrence of such circumstances, in turn, may lead to unnecessary loss of sales of the particular hair care composition brand for the manufacturer. Accordingly, there exists a need for a method of treating a fibrous substrate which comprises the selection of an appropriate substrate treatment composition that is designed to provide or to restore desired physical or cosmetic characteristics to the fibrous substrate.
In turn, there exists a need for a method of assessing characteristics of a fibrous substrate which easily, quickly, accurately, and economically provides information about the physical or cosmetic characteristics of the fibrous substrate. Such information may then be used to guide selection of an appropriate substrate treatment composition in a method of treating a fibrous substrate. However, known methods of assessing characteristics of a fibrous substrate do not provide accurate and consistent results.
For fibrous substrates comprising keratinous fibers, such as human hair, methods of assessing a physical or cosmetic characteristic of the hair typically involve taking a single measurement of some parameter associated with the characteristic at some arbitrary position along the length of the hair. That single measurement is then often compared against a known value of that parameter for a separate control sample of hair having that characteristic. Such assessment methods may not be accurate or may not provide consistent and repeatable results because they fail to account for at least several factors. First, many physical or cosmetic characteristics of hair are affected by environmental conditions, such as temperature and relative humidity. Second, a single physical or cosmetic characteristic of hair may vary along the length of that hair from root to tip. Third, many physical or cosmetic characteristics of hair may inherently vary among different individuals or groups of individuals (i.e., one “control value” may not fit all individuals). As a result, a need still exists for a method of assessing characteristics of a fibrous substrate that provides accurate and consistent results by accounting for the above factors.